Improvements in the field of telephony during the last quarter century have permitted an increasing number of telephone calls to be served on a fully automated or partially automated basis. These improvements have resulted in better customer service while at the same time allowing the more economical provision of telephone services.
Some of these improvements concern serving toll calls orginated at coin pay stations with a minimum of operator intervention.
One such prior art system is disclosed in A. E. Joel, Jr. U.S. Pat. No. 2,676,209, issued Apr. 20, 1954. In this system a plurality of magnetic tape telegraphones provided coin deposit request announcements. Each coin station included signal generators controlled by coin deposits for generating distinct combinations of two frequencies which identified the type of coin deposited (i.e., nickel, dime, or quarter). More specifically, at the beginning of a call, a selected one of the telegraphones was enabled to provide a message to the calling coin subscriber indicating, for example, "Please deposit 10 cents." Responsive to this announcement, the calling subscriber would deposit a dime or two nickels and then the appropriate dual frequency tones would be generated in the coin station and conveyed to a coin tone detector at the serving telephone office which would accumulate the amount deposited as indicated by the received dual frequency tones. When the requisite deposits were detected, the call was completed. Thus, no operator intervention was normally required; however, if an insufficient deposit was received, then a monitoring operator was connected to the calling subscriber to resolve any problem which apparently arose. This system appears to be effective; however, it failed to satisfactorily deal with the problem of detecting coins deposited during automated announcements. If a subscriber deposited a coin during an announcement, then the coin might not be detected by the coin tone detector because of interfering voice signals from the announcement circuit. Moreover, the announcement could possibly inadvertently trip the coin tone detector.
Another automated coin system is described in A. E. Joel, Jr. U.S. Pat. No. 2,761,900, issued Sept. 4, 1956. This system is an improvement on the above-mentioned Joel patent and provided means for recalling the calling party at the termination of a coin call to collect overtime deposits. Also provided were means for changing the charge rates for different telephone calls during the duration of present call connections. This system also suffered from the same disadvantage as its predecessor-- i.e., potential interference between announcements and the detection of coin tones indicative of coin deposits.
Another fully automated coin system is disclosed in N. R. Shaer U.S. Pat No. 3,453,389, July 1, 1969. The Shaer system is incorporated in a larger, partially automated traffic service position systems (TSPS) disclosed in R. J. Jaeger-A. E. Joel, Jr. U.S. Pat. No. 3,484,560, issued Dec. 16, 1966. In the Jaeger-Joel arrangement, a plurality of trunk circuits are provided intermediate to a local office and a toll office. Incoming coil calls on these trunk circuits requiring operator intervention are routed to an operator via a switching network. The system controller called the SPC analyzes the calling and called digits and automatically generates time and charge information for the coil call. This information is displayed at the operator's position. The operator then informs the calling subscriber of the requisite charges and listens for distinctive tones generated at the coin station responsive to the deposit of coins thereat. While the operator listens for the tones to determine whether or not the requisite amount has been deposited at the coin station, the system completes the call through the trunk circuit to the toll office and finally to the called station.
In the Shaer system, announcement equipment and coin tone detectors were added to the switching network in the Jaeger-Joel system, in an effort to fully automate the servicing of customer-dialed toll calls from coin pay stations. More specifically, after a digit receiver received the appropriate calling and called information from the local office, and SPC generated ths usual time and charge information. However, instead of supplying this information to an operator, the SPC controlled the network to connect the trunk to an automatic announcement circuit. This circuit then provided the appropriate announcement such as "Please deposit 60 cents". Moreover, the coin stations in the Shaer system were modified as disclosed in E. R. Andregg et al. U.S. Pat. Nos. 3,146,312; 3,170,039; and 3,116,370. Now a number of tone pulses (bursts) were generated for each deposited coin. One pulse was generated for a deposited nickel, two pulses for a dime, and five pulses for a quarter. Coil tone receivers were provided in the Shaer arrangement for detecting these series of pulses to identify the coils deposited in the coil station. To elaborate, first the network was controlled to establish a connection to the announcment circuit and, then after the termination of the announcement, a new connection was established to a coin tone receiver. When the requisite deposit amount was detected, the call was completed without operator intervention.
The Shaer system appears to provide an effective and economical mechanism for automating coin calls. However, a fully automated coil system must be designed to accommodate all idiosyncracies, quirks, pranks and possible mistakes of a large constituency of users having variable levels of user skills. For example, the Shaer system was not adapted to detect coin deposits during annoucements. When a calling subscriber routinely calls the same destination from a coin station, the calling subscriber may well be aware of the requested deposits, and impatiently may make deposits during the annoucements.
It is an object of this invention to provide for the detection of coin tones during announcements, provided either by automatic announcement circuits or by monitoring operators.
It is a further object of this invention to detect coin deposits free from any interference caused by annoucements.